Almost a month ago, I installed thermometers to record temperatures in the firebox, heat collector & flue piping.
Full firebox 2-8 hrs burn time--constant 900-1050F
Back in Jan with above normal ambient temps I reduced the firebox nearly 33%.
Reduced firebox 2-8 hrs burn time--constant 650-725F
I am amazed at the constant temperature I will record in the firebox after the initail heat generated from a refill settles down. This proves the superiority of a coal stove for heating purposes. You will obtain a very steady and constant temperature for a long period of time.
Shortly after a refill with ash door open, I will see 1000-1150F with 400-450F in the heat collector and 300F+ in the flue pipe. But these numbers are only occur with full draft and obviously I cannot allow the unit to continue to build heat with the door open as ithe firebox temp will become dangeroulsy high.
I am very pleased with this unit. Some of you may recall I had just purchased it new late in Dec to replace an older Mark III. The SF-250 is installed in my basement with the heat collector piped to to first floor living area. Durning the day I do turn off the fan motor and plenty of heat will easily rise out of the heat collector thus adding savings to my heating costs this winter. This season, I have $525 invested in solid fuel. I have friends who burn natural gas spending $300-$400 per month. Incredible! Enough said.